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Biomedical subjects

M Fritzsche

Publications and source records attributed to M Fritzsche.

12 recordsLinked to original sources
PubMed2006

In vitro investigation of the geometric contraction behavior of chemo-mechanical P-protein aggregates (forisomes).

We investigated the contracting behavior of forisomes from Vicia faba by carrying out precise measurements of their changing geometric parameters in vitro in the absence and in the presence of dissolved oxygen. Furthermore, we investigated the fine structure of forisomes by scanning electron microscopy. For the first time, single forisomes were titrated with Ca(2+), protons, and hydroxide ions recording the complete progression of their contractions. An apparent Ca(2+)-binding constant of (22+/-3) muM was calculated from two complete titration curves. The forisomes also contracted in the presence of Ba(2+) and Sr(2+) ions, but the amplitudes of contraction were smaller under the same measuring conditions. The time taken to change from the longitudinally expanded into the longitudinally contracted state was up to 2 s shorter in 10 mM Ca(2+) in comparison to 0.2mM Ca(2+). However, the contraction time was prolonged by decreasing the Ca(2+) concentration. In the absence of dissolved oxygen, the transition between the two final states of the forisomes was almost reversible and the amplitude of contraction remained almost constant during the first 25 contraction cycles. In the presence of dissolved oxygen the forisomes denaturated after a few cycles and lost their ability to contract, just after only a few cycles with 10 min in the contracted state. Denaturation of the forisomes occurred appreciably in the contracted state. We propose a cycle process to explain the thermodynamic basis of the Ca(2+)-induced contraction and its reversal by EDTA. Reducing the pH-value from 7.3 to 4.0 caused the forisomes to shorten by approximately 15%, while increasing the pH to 11.0 caused them to shorten by 28 to 30%. In both cases, the increases of the forisomes volume were greater than during the Ca(2+) induced contraction. The pH values of 4.7+/-0.3, and 10.2+/-0.2 marked the inflection points of the acid base titration of different forisomes.

Biomechanical Phenomena↗
PubMed2003

The origin of brain asymmetry and its psychotic reversal.

Ontogenetic brain-asymmetry and its reversal in schizophrenia constitute special cases of a more fundamental principle of sensory-motor integration. Transmitted through an immature optical system, asymmetric inputs from the left visual field induce the infant's right hemispheric preference for lower spatial frequencies during early mother-child interaction. The emerging classical features of hemispheric specialisation later in life can be accounted for by a transformation law of the neuronal reference frames based on relativistic non-linear information processing. Accordingly, the asymmetric distributions of the cannabinoid receptor CB1 in the right basal ganglia and the left area of Wernicke reflect the preferences for lateralised posture, positioning, and speech. Epigenetic development of brain asymmetry thus unifies the different aspects related to cradling and breast-feeding, speech- and visuospatial processing, the dimensional conversion of spatiotemporal information and, in the case of a dysbalanced cannabinoid system, its psychotic reversal. The predicted right hemispheric shift and the inverse relationship between Kolmogorov entropy and its dimensional embedding (Shannon entropy) has ultimately been confirmed by non-linear EEG analysis of a fluoro-methyl-anadamide induced model psychosis splitting conscious from unconscious mental processes.

Brain↗
PubMed2002

Impaired information processing triggers altered states of consciousness.

Schizophrenia, intoxication with tetrahydrocannabinol (Delta-THC), and cannabis psychosis induce characteristic time and space distortions suggesting a common psychotic dysfunction. Since genetic research into schizophrenia has led into disappointing dead ends, the present study is focusing on this phenotype. It is shown that information theory can account for the dynamical basis of higher sensorimotor information processing and consciousness under physiologic as well as pathologic conditions. If Kolmogorov entropy (inherent in the processing of action and time) breaks down in acute psychosis, it is predicted that Shannon entropy (inherent in the processing of higher dimensional perception) will increase, provoking positive symptoms and altered states of consciousness. In the search for candidate genes and the protection of vulnerable individuals from cannabis abuse, non-linear EEG analysis of Kolmogorov information could thus present us with a novel diagnostic tool to directly assess the breakdown of information processing in schizophrenia.

Cannabis↗
PubMed2001

Sleep deprivation as a predictor of response to light therapy in major depression.

BACKGROUND: While the majority of depressed patients benefit from total sleep deprivation (TSD), light therapy is regarded as a first-line treatment only for seasonal affective disorder (SAD). The results of light therapy in nonseasonal major depressive disorder have been non-conclusive. We examined the correlation of TSD response and light therapy response in major depressed patients. METHODS: 40 inpatients with major depressive disorder (seven with seasonal pattern, 33 without seasonal pattern) were deprived of a night's sleep. The TSD responders, as well as the TSD nonresponders, were randomly assigned to receive adjunct light therapy either with bright white light (2500 lux) or dim red light (50 lux) during 2 weeks beginning on the third day after TSD. RESULTS: The 20 TSD responders improved significantly better under the light therapy than the 20 TSD nonresponders (according to the Hamilton Depression Rating Scale and the self-rating depression scale Bf-S; v. Zerssen). LIMITATIONS: No significant difference could be found between the two light intensities. Since the patients were additionally treated with medication an interaction with the two adjunctive therapies cannot be excluded. CONCLUSION: Our results indicate that a positive TSD response in major depressed patients can be predicative of beneficial outcome of subsequent light therapy.

Adult↗
PubMed2001

Are cannabinoid receptor knockout mice animal models for schizophrenia?

Schizophrenia is a devastating psychiatric disorder with a high prevalence worldwide. There is therefore a need for animal models allowing the development of new therapeutic interventions and reliable diagnostic tests. In the temporal domain, cannabinoid receptor gene (CB1) knockout mice exhibit behavioural alterations, which parallel symptoms in schizophrenia, cannabis intoxication and dopamine D2 activation. While a specific nucleotide homology between CB1 and D2 accounts for the pathophysiology, pre-inserted spirochaetal DNA on the polyadenylation signal of CB1 reveals the aetiology of schizophrenia. If, in analogy to thalassaemia, mutations occur within this 3' regulatory domain, the genetic expression of CB1 is disrupted and sequential information lost in time. CB1, previously unrecognized as a candidate gene, thus unifies the different aspects of schizophrenic psychosis: cannabis-induced model psychosis, disrupted information processing, spatio-temporal distortions and other psychotic symptoms, disturbed neuronal migration, schizophrenic brain disorder, familial transmission, and prenatal infection by Borrelia burgdorferi.

Animals↗
PubMed2001

[Sleep deprivation as a predictor of response to light therapy in major depression].

Light therapy (LT) is regarded as the treatment of choice for seasonal affective disorder (SAD). In nonseasonal depression the results of light therapy are nonconclusive. Sleep deprivation (SD), however, is effective in 50-60% of the patients with major depression. The predictive value of Total Sleep Deprivation (TSD) for the treatment outcome of antidepressiva has been already examined. Purpose of the present study was to test whether light therapy is more beneficial in TSD responders than in TSD nonresponders. 40 inpatients with major depressive disorder completed one night of TSD. Twenty TSD responders and 20 TSD nonresponders were randomly assigned to 14 days of bright light therapy (2500 lux, 7-9 a.m.) or 14 days of dim light therapy (red light 50 lux, 7-9 a.m.). Manova with repeated measurements revealed a significant difference in the course of depression over the time between TSD responders and nonresponders, but no significant difference between bright and dim light. Questions of placebo effect, of SAD and of personality variables as predictors of response to SD and LT are being discussed.

Adult↗
PubMed2000

Neurophysiologic tests during antidepressive treatment - an exploratory study.

This is a non-randomized exploratory study showing the sensitivity of neurophysiological parameters for autonomic side-effects during the application of antidepressant drugs. Inpatients on tricyclic antidepressants (TCA: amitriptyline or doxepine), inpatients on serotonine-reuptake inhibitors (SSRI: fluvoxamine or paroxetin) and a control group of healthy volunteers underwent neurophysiological examination. The treatment group was investigated after at least 7 days of continuous treatment with the final dose. Adjustment of the autonomic nervous system was studied, first, by measuring latency and amplitude of the sympathetic skin response (SSR), elicited by electric stimuli and by deep inspiration, and second, by analysis of the heart rate variation (HRV) during rest and inspiration. Relevant affections of the peripheral parts of the reflex arc under discussion were excluded by taking the nerve conduction velocity (NCV) and F-wave referring to cervical segment C7. In total, 48 individuals were examined. The TCA group showed delayed latencies and smaller amplitudes of the SSR in comparison with the controls. In the SSRI group, these parameters did not differ significantly from those of the controls. Analysis of HRV put further emphasis on the impaired adjustment of the autonomic nervous system in the TCA group. To sum up, our test battery indicated a specific vegetative alteration due to TCA.

Adult↗
PubMed1990

Serological survey of human cysticercosis in Irianese refugee camps in Papua New Guinea.

In 1984, over 10,000 refugees left the Indonesian province of Irian Jaya, and thus possibly imported Taenia solium taeniasis/cysticercosis into Papua New Guinea, which was believed to be free of T. solium until 1966. In a serological survey carried out in 1986, 50 refugees originating from areas endemic for T. solium and 171 patients from other areas with symptoms suggesting the possibility of cysticercosis were examined. As a sensitive prescreening technique an ELISA was used with a crude antigen extract obtained from T. solium metacestodes of pig origin. Of 221 persons investigated, 79 (36%) were positive in ELISA. For excluding frequently occurring cross-reactions in ELISA, Western-blotting (or EITB, enzyme-linked immunoelectrotransfer blot) was employed. In this test the demonstration of antibody activity to the 26 or the 8 kilodalton band has been proved to be species-specific for T. solium cysticercosis. One from 79 patients positive in ELISA was simultaneously positive (26 and 8 kDa) in Western blot, corresponding to the first case found in Papua New Guinea with a highly probable T. solium cysticercosis. This patient, originating from an endemic area in Irian Jaya, had immigrated into Papua New Guinea in 1980. The present work emphasizes the need for using highly specific immunodiagnostic techniques in seroepidemiology of larval cestode infections. T. solium taeniasis/cysticercosis remains a risk for Papua New Guinea, and refugees originating from endemic areas should be regarded as potential carriers of T. solium.

Animals↗
PubMedDate not supplied

Altered Ca(2+)-homeostasis in single T-lymphocytes of depressed patients.

After stimulation of T-lymphocytes from healthy volunteers with the mitogen phytohemagglutinin (PHA) 40% of the cells exhibit an oscillatory increase in intracellular calcium concentration ([Ca2+]i). During depression the number of cells responding to PHA is reduced to 20%. These cells show a marked decrease in [Ca2+]i-reaction to stimulation and flattened oscillations. This reduction of mitogen-induced Ca2+ signals in T-cells of depressed patients appears to be a reliable state marker in depressive illness and is reversed upon successful treatment with interpersonal psychotherapy (IPT).

Adult↗